Random Numbers with no duplicates

[Anon]

Does anyone have a class or an idea that will allow me to generate about 1200 random five digit numbers with no duplicates?

I have an employee number in the field that is six digits long and is exlusive so possibly there is a formula that can use that seed to generate the 5 digit number but I have tried a few algorithims and I get at least some duplicates.

Any ideas???

Thanks

Brian

[Anon]

Im an electronic engineer and I was shown a random generator that produces numbers in a random order but with no repeats. It was a binary feedback loop. if you had a number like 1010 (1234) . You'd take the 3rd and 4th digit then XOR them to produce the new 1st digit and the old 4th would drop off the end. So (1010) would take 1 and 0 giving 1 and so you would get 1101 then 1110 then 1111 then 0111 and so on. If you can convert the binary to decimal your in business. an 11 bit binary number will give you 2048 combinations in a random order with no repeats. If you can help me with my checkbox record selection I'd appreciate it.

Kevin Monk

[Anon]

<?php

// Seed random generator
mt_srand( (double)microtime() * 1000000 );

function generate_unique( $num, $len ) {

// Init array
$number_array = array();

// Set start and end values
$start = (int)str_pad( 1, $len, 0 );
$end = (int)str_pad( '', $len, 9 );

while( sizeof( $number_array ) < $num ) {

  // Could take a while
  set_time_limit(10);

  // Add a new 5 digit number to the array
  $number_array[] = mt_rand( $start, $end );

  // Whip out the duplicates
  array_unique( $number_array );

}

return $number_array;
}

$random_numbers = generate_unique( 1200, 5 );

?>

[Anon]

I can certainly understand the need for uniqueness here, but what does having them semi-random accomplish?